Cbp调控PI3K/AKT/mTOR在肥胖相关乳腺癌化疗耐药中的作用及机制

There were some clinical reports about obesity associated breast cancer chemoresistance, but little experimental evidences and unclear mechanisms. Our previous studies found that adipose-derived stem cells promoted the transmembrane adaptor protein PAG1/Cbp expression which modulating the PI3K、p-AKT、p-mTOR signal pathway resulting in promoting tumor progression and anti-apotosis. It prompted that Cbp may be a novel, promising chemosensitization target for breast cancer. At present, there is no report about Cbp associated pathway modulating breast cancer chemoresistance. According to these results, we propose that obesity microenvironment modulate PI3K/AKT/mTOR expression indirectly through activating Cbp expression resulting in promoting breast cancer proliferation, EMT and chemoresistance. In order to further investigate the mechanisms and explain the clinical problems, at the levels of cells, tissue specimen and animals, referring the bioinformatics analysis, we plan to verify the pathway between Cbp and PI3K/AKT/mTOR using the western-blot and protein immunoprecipitation method, and evaluate the predictive value of ASCs and Cbp in chemotherapy reaction by building obese rat mode and testing the chemosensitivity in vivo. Our project will investigate the new mechanisms of obesity associated breast cancer chemoresistance from the new view of transmembrane adaptor protein in order to find more precise therapy target and to provide more effective predictive index for clinical decisions.

肥胖相关乳腺癌的化疗耐药已有临床报道，但机制尚不明确。我们前期研究发现，在脂肪干细胞（ASCs）模拟的肥胖微环境中，跨膜接头蛋白Cbp调控PI3K、p-AKT、p-mTOR对乳腺癌细胞具有促肿瘤和促耐药作用，提示Cbp可能是一个新的化疗增敏的治疗靶点。目前，未见Cbp相关通路调控乳腺癌耐药的报道。据此，我们提出假设：肥胖微环境，通过激活Cbp，调控PI3K/AKT/mTOR通路，促进乳腺癌的增殖、EMT和耐药。本课题拟在细胞、组织、动物水平，参考生物信息分析，采用western-blot和蛋白免疫共沉淀方法，明确Cbp与PI3K/AKT/mTOR蛋白之间的信号通路，构建肥胖鼠模型进行体内药敏检测，评价ASCs及Cbp蛋白对乳腺癌化疗疗效的预测价值。本研究从跨膜接头蛋白的新角度，探讨肥胖相关乳腺癌耐药的新机制，为药物治疗寻找更精确的治疗靶点，为临床决策提供更有效的预测指标。

本课题前期实验，在体外模拟肥胖肿瘤微环境，发现敲减PAG1/Cbp，可下调p-Src、PI3K、p-AKT 及p-mTOR 的表达，并抑制乳腺癌的增殖、逆转EMT 和耐药。其实验主要在HR阳性的乳腺癌细胞株上检测完成。根据实验计划，我们在HR阴性的三阴性乳腺癌细胞株中，再次敲减PAG1/Cbp，以期进一步验证前期实验结果。三阴性乳腺癌细胞的功能学实验已完成，并取得满意实验结果。在实验验证过程中，我们发现PAG1基因与PRRC1基因存在紧密的功能关联，可能协同参与乳腺癌细胞的增殖，逆转EMT和耐药。为探究PRCC1基因与三阴性乳腺癌及PAG1基因的内在关联，我们进一步构建了PRCC1干扰RNA，检测了三阴性乳腺癌敲减PRCC1基因后的细胞功能学表现。后期，拟探究乳腺癌PAG1-PRRC1基因的内在分子机制。